Am Wed, 02 Mar 2016 19:46:33 +0100 schrieb [email protected]: > which distro are you using ?
Source Mage GNU/Linux, a venerable (at least as old as gentoo) but
admittedly rather obscure source-based distro. And with „my“ I mean
that I'm one of the packagers writing scripts to build software in this
distro.
> > What libraries for OSS and LADSPA are referred to here? Those APIs
> > don't come with libraries.
>
> It refers to the dev-lib, sometimes called *-dev.
> Their precise names depend on the distribution you're running hence my
> question above
>
> As an example, on a Debian system they are :
> - liblrdf-dev (LADSPA one IIRC)
> - libjack-dev or libjack-jack2-dev (JACK)
> - oss4-dev (OSS)
That's one reason for me to use a source-based distro: There are no
separate *-dev packages. When I install liblrdf, this gets me a full
build including headers and *.so/.a/.la for linking.
> Do you really need a support for OSS ? If you are running a linux
> distro,
> ALSA is use most of the time.
I don't really need OSS right now. It is just one option offered by
Hydrogen and in Source Mage, those options are exposed to the user. The
empasis is on user choice in the builds (not on preselecting everything
that is deemed necessary or useful).
> > largely untested nowadays, but it is still a simple API that works on a
> > range of systems. And there is no library to link to that I'm aware of.
>
> This is uncorrect. See my previous point about OSS4-dev on Debian.
Hm, perhaps it changed from the last time I used OSS4, but I don't
remember a library entering the game. OSS is a kernel-based sound
system with an API that works on file descriptors with ioctls. That's
the beauty of it: Just including a header to get the proper ioctl
codes, opening a file, and then just write your data to it. OSS was the
first sound API I programmed for and I don't remember linking in any
library. The OSS4 stuff brought some tools with it that enabled mixing
between applications with some GUI. But that was years ago. Was still
awesome, from a technical perspective. No messing with heavy userspace
audio daemons or libraries. But I digress.
Same with LADSPA: There is a header that defines the binary format. You
use dlopen() to open the plugins. You need tolink with libdl for that,
but not with anything LADSPA-specific. Disclaimer: I also wrote simple
LADSPA loading and processing code for a project of mine;-)
So, when I say library, I really mean a library (archive, shared
object) file, not a distro package providing them. I do have
/usr/include/linux/soundcard.h
and
/usr/include/ladspa.h
and as far as I know, those files should be enough to build an
application using OSS or LADSPA plugins.
The liblrdf part is about parsing metadata of plugins, not the plugins
themselves. So I presume things are not well unless the hydrogen build
activates WANT_LADSPA.
What is it looking for, exactly? Not really distro packages, I hope?
Looking at CMakeLists.txt:
FIND_LADSPA(LADSPA ladspa.h noise)
FIND_HELPER(OSS oss sys/soundcard.h OSSlib )
I see that ladspa installs a plugin
/usr/lib/ladspa/noise.so
So the build looks for that one? This is strange, as this really is no
development file but a plugin to load at runtime. It is not necessay to
load other plugins. Perhaps I need to set an environment variable to
make hydrogen look in /usr/lib/ladspa (which I supposed is the default
path for plugins, searched by any app if no other setting is present).
An interesting question for me is if it makes sense to give WANT_LADSPA
without WANT_LRDF. Will hydrogen support LADSPA plugins without the
metadata fluff of lrdf?
As for OSS, this looks specifically for binaries of OSS4, then? Mind
that there is still OSS3 support in the kernel (at least via OSS
emulation by ALSA). So perhaps it should be made more clear that this
really about the 4Front OSS4.
Alrighty then,
Thomas
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